Numerous prior art processes have been proposed for the preparation of glycol esters of carboxylic acids by reacting an olefinically unsaturated compound such as ethylene and oxygen in the presence of a carboxylic acid and various catalyst systems including tellurium and other variable valent metal compounds together with a halogen source to provide halide ions in solution under oxidation conditions.
Literature articles, namely, Kogyo Kagaku Zassi, Vol. 73, page 1987, (1970) by M. Ogawa, C. Inone and R. Ishioka; Journ. Prakt. Chem., [4], Vol. 1, page 33 (1954) by H. Funk and Weiss and Angew. Chem. Ind. Ed. Eng., Vol. 10, page 73 (1971) by H. J. Arpe and H. Kuckertz show that tellurium tetrachloride adds across the carbon-carbon double bond in propylene to give substituted organyl tellurium trichloride, and in ethylene and in propylene when the reagents are mixed in stoichiometric ratio, to give bis(2-haloalkyl)tellurium dichlorides respectively.
In an article by M. Ogawa, Bull. Chem. Soc. Japan, Vol. 41, page 3031 (1968) and the Angew. Chem. Ind. Ed. Eng. Vol. 10, (1971) article noted above, there is described the thermal decomposition of bis(2-chloroalkyl)tellurium dichloride which when decomposed gave only olefins, various chloroalkanes, chloroolefins, hydrogen chloride and inorganic tellurium compounds and therefore provided no practical application for the preparation of glycol esters or the respective glycol such as ethylene or propylene glycol. As described hereinafter, the thermal decomposition of bis(2-chloroethyl)tellurium dichloride in acetic acid gave only a trace amount of ethylene and no glycol ester product.
There is no known prior art which describes the thermal decomposition of the organic bromoalkyl tellurium compounds of the present invention.
Contrary to the teachings of the prior art and investigative findings, it has surprisingly been discovered that organic bromo alkyl tellurium compounds selected from 2-bromoalkyltellurium tribromide and bis(2-bromoalkyl)tellurium dibromide compounds can be thermally decomposed in a carboxylic acid medium, preferably in the presence of oxygen, to give excellent yields of carboxylic acid esters, such as 2-bromoethylacetate and ethylene glycol diacetate, and at the same time essentially avoid the problems of the dissociation products encountered by prior processes.